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Myth about WPA ( How it is done ), Windows Product Activation Technique

Microsoft's plans to stop people pirating the next version of Windows have suffered a setback.

A German computer magazine has found weaknesses in the piracy protection system built into Windows XP.

The weaknesses could mean that in up to 90% of cases users can circumvent the copy protection system.

But Microsoft said that the protection system would be much stronger and harder to defeat when the final version of XP is released later this year.

Component count

In a bid to combat piracy Microsoft is introducing a product activation system into the XP versions of its software. Activating a product involves contacting Microsoft for an identification number that is then combined with the serial numbers of the components inside your computer to create a unique identifier.

it would be possible to 'activate' nearly 90 percent of home-user machines without Microsoft knowing anything about it

Mike Hartmann, Tec ChannelBig changes to the hardware in a machine could mean that users have to contact Microsoft for a new identification number to re-activate their software.

By tying software to individual machines Microsoft hopes to stop its products being run on more machines than they are licensed for.

But now German computer magazine Tec Channel has analysed the product activation system that is being used in the test, or beta, versions of Windows XP and found that, in many cases, it can be compromised by making simple changes.

File fiddling

When Windows XP is first installed and activated it generates a file called wpa.dbl that stores information about the configuration of your machine.

Changes to any one of the ten components or serial numbers that this file watches are logged. When three changes have been made the wpa.dbl file is deleted forcing the user to contact Microsoft to reactivate the software.

But Mike Hartmann, a journalist at Tec Channel, has found that the ability of the wpa file to spot piracy can be easily compromised.

In tests Mr Hartmann installed and activated XP, then saved a version of the wpa file that was generated. He then changed components on the test machine so XP had to be re-activated. However, copying the old version of the wpa file back in the Windows system directory stopped requests for reactivation.

Piracy problems

The activation was also compromised when XP was fooled into thinking that a desktop PC was a laptop in a docking station, rather than a self-contained machine. In this configuration some components that wpa watches would be in the docking station rather than the portable computer. XP dutifully ignored any changes made to these components.

In total Mr Hartmann found a way to make the Windows XP activation technology ignore six of the ten components that it monitors. Mr Hartmann said another two can vary in only a small number of ways among all machines making it possible to create a "universal" wpa file that should activate XP on most PCs.

"With some smart tools that do automatic matching of hardware and activation-files it would be possible to 'activate' nearly 90 percent of home-user machines without Microsoft knowing anything about it," Mr Hartmann told BBC News Online.

Mr Hartmann expects to see activation file sites springing up on the web that offer wpa files tied to PCs with particular configurations thus ruining Microsoft's chances of cutting piracy.

"Should Microsoft stick with current version of wpa they will have wasted lots of money for call-center-employees, webservers and the technology itself," he said.

But a spokeswoman for Microsoft said that the version of the activation system that is in the pre-release versions of Windows XP is weaker than that which will ship with the finished version.

"The things that have been highlighted as a way of potentially bypassing activation will not be in the final code," said the spokeswoman. "The final code is going to be very different to what we have now."

"Product activation is not completely fixed in place at this time," she added.

Hacking WindowsXP Product Activation

Basic Issues

The file wpa.dbl in the directory system32 contains information on the system at the time of the Activation. If more than three hardware components are changed, Windows XP will notice it and delete wpa.dbl. With that the user shall be forced to activate XP anew. You do not get another 30 days of time, though, to activate again (in RC1 it is a fortnight). Instead XP takes the date of the installation as a basis. That means you have to activate immediately to run XP again, if the installation took place 30 days ago.

Volume serial number of the system volumes (displayed with dir-command)MAC address of the network card (displayed with netstat -r -n)Identification string of the CD ROM driveIdentification string of the displaysCPU serial numberIdentification string of the system's hard diskIdentification string of the SCSI host adapterIdentification string of the IDE controllerString of the processor modelRAM size1 = docking station, 0 = without docking station

First Tests

For a beginning we first of all saved the file wpa.dbl and then replaced the graphics card and the network card. As expected Windows XP was cooperative, so we could work without any disturbance. The first surprise showed up as we replaced the Celeron with a Pentium III: Suddenly Windows XP wanted to activate anew although we only changed three components.The answer to the riddle is to be found in the serial number of the processor. Replacing the processor did not only change one but already changed two pieces of hardware information. For us that means to restart the computer and to switch off the serial number in the BIOS. Nonetheless XP insists on the Activation. A glance at wpa.dbl shows the reason why: Apparently XP put the file back in a non-activated condition. We again restart the computer, boot into DOS and copy the saved wpa.dbl back into the system directory of XP. With the next start of XP, the demand for Activation has disappeared. Evidently, wpa.dbl is the central authority to decide whether or not Activation already took place.

We re-install Windows XP on our computer from the ground up, using the very same product key. Nevertheless, the computer gets another product ID, as the last three digits are generated randomly. Although the product ID changed, Windows can be activated by copying the saved file wpa.dbl into the appropriate directory. Our next try brings an even bigger surprise: The Activation still works although we use a completely new product key for the installation.

Forged Hardware

These results kept in the back of our minds we try to activate Windows XP on another computer by copying the file wpa.dbl. First of all we adapt the volume ID of the new computer by means of freeware tools. The command line volumeid c: 3333-3333 changes the corresponding coefficient of the new system: The first component of Microsoft's protection is canceled.

With some network cards it is possible to adjust the MAC manually by means of the driver. The corresponding option in the register Advanced is called "Network Address" or "Locally administered Network Address".

So meanwhile we succeeded in switching off two components of the Activation by pretending another network address to the new system. The CPU serial number is switched off anyway, both computers do not have a SCSI host adapter and the memory is of the same size with both of them. With that altogether five sections of the hardware ID are identical.Six actually, for both computers are not "to be docked". The latter gives us a bold plan...Notebook of Eight Kilogrammes

What would happen if we tell the operating system that the computer is a notebook? This option can be toggled in the hardware profile of the device manager.

Can Microsoft be tricked that easily? Yes it can! After the next restart of the computer the analysis of the installation ID makes clear that suddenly the graphics card and the IDE/SCSI controller are no longer used to calculate the hardware ID.So only three more differences in the configuration of the hardware remain:

Identification of the hard diskIdentification of the CPUIdentification of the CD-ROM drive

Because these three components are allowed to be different without XP insisting on a new Activation, this should be sufficient. So we copy the file wpa.dbl into the system32 directory of the second computer and start Windows XP. In the start menu it still says "Activate Windows". But when you call it up, you get your just reward though:

Windows XP enlists ten hardware components to calculate the installation ID, but six of them can be canceled without any problems:

Component To be canceled byVolume ID Adapted by means of toolMAC address Tuned by means of driverGraphics card Switch over to docking stationCPU serial number Switch off in BIOSSCSI host adapter Switch over to docking stationIDE controller Switch over to docking station

Important: A LAN does not tolerate two computers with the same MAC address.

Only four components are working almost effectively:

Component Size of bit field

Hard disk 7CPU type 3CD ROM 7RAM size 3

Two fields are coded with three bits and two with seven bits. Because in each field the coefficient 0 is impossible, 7*7*127*127=790321 possibilities remain for the file wpa.dbl. As only three components are allowed to change from the moment of Activation onwards, you can take the weakest fixed component for a "Universal Activation".

The CPU type or the RAM size present themselves here as the best solution. It is more than sufficient to only once activate a computer with 128 MBytes of RAM at Microsoft's. With its file wpa.dbl you can then "activate" all other computers of the same memory size.

Conclusion

With its technology of Activation Microsoft wants to thwart the user who occasionally copies software. Up to a certain degree this may still work. But by means of the above described steps nearly everybody can activate his own XP merely by getting a corresponding wpa.dbl file. There certainly will exist some web sites in the near future where the user can comfortably download "his"wpa.dbl.

Should the current procedure of Activation remain, then Microsoft will spend a lot of money like water for technology, web servers and call centers without any considerable success. It would be much more lucrative to drop the Activation and to lower the price for XP.

Microsoft did not comment on the weak points of the Activation until now. But probably their statement goes as follows: "In its final version WPA will look completely different. We did not implement these steps in the RC1 for only one reason, that is not to annoy the testers."

But it definitely is a fact that in-between the Release Candidates and the real Release normally only bugs are rectified. May sharp tongues call the WPA itself a bug, in our opinion it is nothing more but an example of bad programming.

Inside Windows Product Activation

A Fully Licensed Paper

July 2001

Fully Licensed GmbH, Rudower Chaussee 29, 12489 Berlin, Germany

ht*p://www.licenturion.com

>> INTRODUCTION

The current public discussion of Windows Product Activation (WPA) ischaracterized by uncertainty and speculation. In this paper we supplythe technical details of WPA - as implemented in Windows XP - thatMicrosoft should have published long ago.

While we strongly believe that every software vendor has the right toenforce the licensing terms governing the use of a piece of licensedsoftware by technical means, we also do believe that each individualhas the right to detailed knowledge about the full implications of theemployed means and possible limitations imposed by it on softwareusage.

In this paper we answer what we think are currently the two mostimportant open questions related to Windows Product Activation.

* Exactly what information is transmitted during activation?

* How do hardware modifications affect an already activatedinstallation of Windows XP?

Our answers to these questions are based on Windows XP ReleaseCandidate 1 (build 2505). Later builds as well as the final version ofWindows XP might differ from build 2505, e.g. in the employedcryptographic keys or the layout of some of the datastructures.

However, beyond such minor modifications we expect Microsoft to clingto the general architecture of their activation mechanism. Thus, weare convinced that the answers provided by this paper will still beuseful when the final version of Windows XP ships.

This paper supplies in-depth technical information about the innerworkings of WPA. Still, the discussion is a little vague at somepoints in order not to facilitate the task of an attacker attemptingto circumvent the license enforcement supplied by the activationmechanism.

XPDec, a command line utility suitable for verifying the presentedinformation, can be obtained from http://www.licenturion.com/xp/. Itimplements the algorithms presented in this paper. Reading its sourcecode, which is available from the same location, is highlyrecommended.

We have removed an important cryptographic key from the XPDec sourcecode. Recompiling the source code will thus fail to produce a workingexecutable. The XPDec executable on our website, however, containsthis key and is fully functional.

So, download the source code to learn about the inner workings of WPA,but obtain the executable to experiment with your installation ofWindows XP.

We expect the reader to be familiar with the general procedure ofWindows Product Activation.

>> INSIDE THE INSTALLATION ID

We focused our research on product activation via telephone. We didso, because we expected this variant of activation to be the moststraight-forward to analyze.

The first step in activating Windows XP via telephone is supplying thecall-center agent with the Installation ID displayed by msoobe.exe,the application that guides a user through the activation process. TheInstallation ID is a number consisting of 50 decimal digits that aredivided into groups of six digits each, as in

002666-077894-484890-114573-XXXXXX-XXXXXX-XXXXXX-XXXXXX-XX

In this authentic Installation ID we have substituted digits that weprefer not to disclose by 'X' characters.

If msoobe.exe is invoked more than once, it provides a differentInstallation ID each time.

Since the Installation ID is the only piece of information revealedduring activation, the above question concerning the informationtransmitted during the activation process is equivalent to thequestion

'How is the Installation ID generated?'

To find an answer to this question, we trace back each digit of theInstallation ID to its origins.

>>> Check digits

The rightmost digit in each of the groups is a check digit to guardagainst simple errors such as the call center agent's mistyping of oneof the digits read to him or her. The value of the check digit iscalculated by adding the other five digits in the group, adding thedigits at even positions a second time, and dividing the sum byseven. The remainder of the division is the value of the checkdigit. In the above example the check digit for the first group (6) iscalculated as follows.

Adding the even digits twice is probably intended to guard against therelatively frequent error of accidentally swapping two digits whiletyping, as in 00626 vs. 00266, which yield different check digits.

>>> Decoding

Removing the check digits results in a 41-digit decimal number. Adecimal number of this length roughly corresponds to a 136-bit binarynumber. In fact, the 41-digit number is just the decimal encoding ofsuch a 136-bit multi-precision integer, which is stored in littleendian byte order as a byte array. Hence, the above Installation IDcan also be represented as a sequence of 17 bytes as in

In this representation of the above Installation ID 'X' charactersagain substitute the digits that we prefer not to disclose. The '0x'prefix denotes hex notation throughout this paper.

>>> Decryption

When decoding arbitrary Installation IDs it can be noticed that themost significant byte always seems to be 0x00 or 0x01, whereas theother bytes look random. The reason for this is that the lower 16bytes of the Installation ID are encrypted, whereas the mostsignificant byte is kept in plaintext.

The cryptographic algorithm employed to encrypt the Installation ID isa proprietary four-round Feistel cipher. Since the block of inputbytes passed to a Feistel cipher is divided into two blocks of equalsize, this class of ciphers is typically applied to input blocksconsisting of an even number of bytes - in this case the lower 16 ofthe 17 input bytes. The round function of the cipher is the SHA-1message digest algorithm keyed with a four-byte sequence.

Let + denote the concatenation of two byte sequences, ^ the XORoperation, L and R the left and right eight-byte input half for oneround, L' and R' the output halves of said round, and First-8() afunction that returns the first eight bytes of an SHA-1 messagedigest. Then one round of decryption looks as follows.

L' = R ^ First-8(SHA-1(L + Key))R' = L

The result of the decryption is 16 bytes of plaintext, which are -together with the 17th unencrypted byte - from now on interpreted asfour double words in little endian byte order followed by a singlebyte as in

As can be seen, the (Raw) Product Key plays an important role ingenerating the Product ID.

>>>> Product Key

The Raw Product Key is buried inside the Product Key that is printedon the sticker distributed with each Windows XP CD. It consists offive alphanumeric strings separated by '-' characters, where eachstring is composed of five characters, as in

FFFFF-GGGGG-HHHHH-JJJJJ-KKKKK

Each character is one of the following 24 letters and digits:

B C D F G H J K M P Q R T V W X Y 2 3 4 6 7 8 9

Very similar to the decimal encoding of the Installation ID the 25characters of the Product Key form a base-24 encoding of the binaryrepresentation of the Product Key. Decoding the Product Key yields amulti-precision integer of roughly 115 bits, which is stored - againin little endian byte order - in an array of 15 bytes. Decoding theabove Product Key results in the following byte sequence.

Of these 15 bytes the least significant four bytes contain the RawProduct Key in little endian byte order. The least significant bit isremoved by shifting this 32-bit value (0x4595FA6F - remember thelittle endian byte order) to the left by one bit position, resultingin a Raw Product Key of 0x22CAFD37, or

583728439

in decimal notation.

The eleven remaining bytes form a digital signature, allowingverification of the authenticity of the Product Key by means of ahard-coded public key.

>>>> Product Key -> Product ID

The three most significant digits, i.e. 583, of the Raw Product Key'snine-digit decimal representation directly map to the BBB component ofthe Product ID described above.

To obtain the CCCCCCC component, a check digit is appended to theremaining six digits 728439. The check digit is chosen such that thesum of all digits - including the check digit - is divisible byseven. In the given case, the sum of the six digits is

7 + 2 + 8 + 4 + 3 + 9 = 33

which results in a check digit of 2, since

7 + 2 + 8 + 4 + 3 + 9 + 2 = 33 + 2 = 35

which is divisible by seven. The CCCCCCC component of the Product IDis therefore 7284392.

For verifying a Product Key, more than one public key is available. Ifverification with the first public key fails, the second is tried,etc. The DD component of the Product ID specifies which of the publickeys in this sequence was successfully used to verify the Product Key.

This mechanism might be intended to support several different partiesgenerating valid Product Keys with different individual private keys.

However, the different private keys might also represent differentversions of a product. A Product Key for the 'professional' releasecould then be signed with a different key than a Product Key for the'server' release. The DD component would then represent the productversion.

which indicates that the first public key (DD = index = 0) matched and123 was chosen as the random number EEE.

The randomly selected EEE component is the reason for msoobe.exepresenting a different Installation ID at each invocation. Because ofthe applied encryption this small change results in a completelydifferent Installation ID.

So, the Product ID transmitted during activation will most probablydiffer in the last three digits from your Product ID as displayed byInternet Explorer or as stored in the registry.

>>> Hardware Information

As discussed above, the hardware configuration linked to theInstallation ID is represented by the two double words H1 and H2.

>>>> Bit-fields

For this purpose, the double words are divided into twelvebit-fields. The relationship between the computer hardware and thebit-fields is given in the following table.

Bit 31 of H2 specifies, whether the bit-fields represent a notebookcomputer that supports a docking station. If docking is possible, theactivation mechanism will be more tolerant with respect to futurehardware modifications. Here, the idea is that plugging a notebookinto its docking station possibly results in changes to its hardwareconfiguration, e.g. a SCSI host adapter built into the docking stationmay become available.

Bits 2 through 0 of H2 are unused and always set to 001.

If the hardware component corresponding to one of the remaining tenbit-fields is present, the respective bit-field contains a non-zerovalue describing the component. A value of zero marks the hardwarecomponent as not present.

All hardware components are identified by a hardware identificationstring obtained from the registry. Hashing this string provides thevalue for the corresponding bit-field.

>>>> Hashing

The hash result is obtained by feeding the hardware identificationstring into the MD5 message digest algorithm and picking the number ofbits required for a bit-field from predetermined locations in theresulting message digest. Different predetermined locations are usedfor different bit-fields. In addition, a hash result of zero isavoided by calculating

Hash = (Hash % BitFieldMax) + 1

where BitFieldMax is the maximal value that may be stored in thebit-field in question, e.g. 1023 for a 10-bit bit-field, and 'x % y'denotes the remainder of the division of x by y. This results invalues between 1 and BitFieldMax. The obtained value is then stored inthe respective bit-field.

>>>> RAM bit-field

The bit-field related to the amount of RAM available to the operatingsystem is calculated differently. The seven valid values specify theapproximate amount of available RAM as documented in the followingtable.

It is important to note that the amount of RAM is retrieved by callingthe GlobalMemoryStatus() function, which reports a few hundredkilobytes less than the amount of RAM physically installed. So, 128 MBof RAM would typically be classified as "between 64 MB and 127 MB".

>>>> Real-world example

Let us have a look at a real-world example. On one of our test systemsthe hardware information consists of the following eight bytes.

0xC5 0x95 0x12 0xAC 0x01 0x6E 0x2C 0x32

Converting the bytes into H1 and H2, we obtain

H1 = 0xAC1295C5 and H2 = 0x322C6E01

Splitting H1 and H2 yields the next table in which we give the valueof each of the bit-fields and the information from which each value isderived.

XPDec is a utility to be run from the command prompt. It may beinvoked with one of four command line options to carry out one of fourtasks.

>>>> XPDec -i

This option enables you to access the information hidden in anInstallation ID. It decodes the Installation ID, decrypts it, anddisplays the values of the hardware bit-fields as well as the ProductID of your product. Keep in mind that the last three digits of theProduct ID contained in the Installation ID are randomly selected anddiffer from the Product ID displayed by Internet Explorer.

The only argument needed for the '-i' option is the Installation ID,as in

XPDec -i 002666-077894-484890-114573-XXXXXX-XXXXXX-XXXXXX-XXXXXX-XX

>>>> XPDec -p

To help you trace the origin of your Product ID, this option decodes aProduct Key and displays the Raw Product Key as it would be used in aProduct ID.

The only argument needed for the '-p' option is the Product Key, as in

XPDec -p FFFFF-GGGGG-HHHHH-JJJJJ-KKKKK

Note that this option does not verify the digital signature of theProduct Key.

>>>> XPDec -v

This option calculates the hash of a given volume serial number. Itwas implemented to illustrate our description of string hashing. Firstuse '-i' to display the hardware bit-fields. Then use this option toverify our claims concerning the volume serial number hash.

The only argument needed for the '-v' option is the volume serialnumber of your system volume, as in

XPDec -v 1234-ABCD

(The volume serial number is part of the 'dir' command's output.)

>>>> XPDec -m

This option calculates the network adapter bit-field valuecorresponding to the given MAC address. Similar to '-v' this optionwas implemented as a proof of concept.

The only argument needed for the '-m' option is the MAC address ofyour network adapter, as in

XPDec -m 00-C0-DF-08-9E-44

(Use the 'route print' command to obtain the MAC address of yournetwork adapter.)

>> HARDWARE MODIFICATIONS

When looking at the effects of hardware modifications on an alreadyactivated installation of Windows XP, the file 'wpa.dbl' in the'system32' directory plays a central role. It is a simpleRC4-encrypted database that stores, among other things like expirationinformation and the Confirmation ID of an activated installation,

a) the bit-field values representing the current hardwareconfiguration,

and

the bit-field values representing the hardware configurationat the time of product activation.

While a) is automatically updated each time the hardware configurationis modified in order to reflect the changes, remains fixed. Hence,can be thought of as a snapshot of the hardware configuration atthe time of product activation.

This snapshot does not exist in the database before product activationand if we compare the size of 'wpa.dbl' before and after activation,we will notice an increased file size. This is because the snapshot isadded to the database.

When judging whether re-activation is necessary, the bit-field valuesof a) are compared to the bit-field values of , i.e. the currenthardware configuration is compared to the hardware configuration atthe time of activation.

>>> Non-dockable computer

Typically all bit-fields with the exception of the unused field andthe 'dockable' field are compared. If more than three of these tenbit-fields have changed in a) since product activation, re-activationis required.

This means, for example, that in our above real-world example, wecould replace the harddrive and the CD-ROM drive and substantiallyupgrade our RAM without having to re-activate our Windows XPinstallation.

However, if we completely re-installed Windows XP, the information inwould be lost and we would have to re-activate our installation,even if we had not changed our hardware.

>>> Dockable computer

If bit 31 of H2 indicates that our computer supports a dockingstation, however, only seven of the ten bit-fields mentioned above arecompared. The bit-fields corresponding to the SCSI host adapter, theIDE controller, and the graphics board are omitted. But again, ofthese remaining seven bit-fields, only up to three may change withoutrequiring re-activation.

>> CONCLUSIONS

In this paper we have given a technical overview of Windows ProductActivation as implemented in Windows XP. We have shown whatinformation the data transmitted during product activation is derivedfrom and how hardware upgrades affect an already activatedinstallation.

Looking at the technical details of WPA, we do not think that it is asproblematic as many people have expected. We think so, because WPA istolerant with respect to hardware modifications. In addition, it islikely that more than one hardware component map to a certain valuefor a given bit-field. From the above real-world example we know thatthe PX-32TS maps to the value 0x37 = 55. But there are probably manyother CD-ROM drives that map to the same value. Hence, it isimpossible to tell from the bit-field value whether it is a PX-32TSthat we are using or one of the other drives that map to the samevalue.

In contrast to many critics of Windows Product Activation, we thinkthat WPA does not prevent typical hardware modifications and,moreover, respects the user's right to privacy.

>> ABOUT THE AUTHORS

Fully Licensed GmbH is a start-up company focusing on novel approachesto online software licensing and distribution. Have a look at theirwebsite at

http://www.licenturion.com

for more information.

Their research branch every now and then analyzes licensing solutionsimplemented by other companies.

Microsoft was not involved in the creation of the paper in anyway. However, we made a draft version available to Microsoft to givethem a head-start. We consider it to be good etiquette to inform avendor of a pending publication related to one his or her products, sothat the vendor is able to prepare an official response.

>> 2. Why should we believe you?

We do not expect you to believe us. That's why we have provided ourcomplete knowledge about WPA and the XPDec utility. Combine both toverify our claims.

>> 3. But Thomas Lopatic, one of your managing directors was born inUnterschleissheim, Germany, which is the town near Munich inwhich Microsoft's European headquarters are located.

This is a nice coincidence. It is in a way understandable - and at thesame time highly amusing to us :-) - that this has given rise torumors about the whole paper being a cleverly planned Microsoftconspiracy.

Thomas was actually born in Karlsruhe, Germany. However, he was livingin Unterschleissheim from the 1970s - i.e. long before Microsoft movedthere - until recently, when he moved to Berlin. That's why somerecords still list Unterschleissheim as the place where helives. Incorrectly interpreting these records led to the rumor thatThomas was born in Unterschleissheim.

>> 4. Does Microsoft downplay the paper?

No, most definitely not. The paper really IS harmless. It does notprovide any information that would help a pirate circumvent WPA.

>> 5. Why did you release details on Windows Product Activation?

We felt that there is a need for facts in the debate about WindowsProduct Activation. Many people suspected that WPA could be abused tospy on end-users. Our paper, however, shows that insensitiveinformation is transmitted during product activation. From this, itcan be seen that the facts that we provide really are a necessarycontribution to the ongoing discussion about WPA.

We think that license enforcement mechanisms will be an important partof the future of software distribution via the Internet. Thus, we dothink that public discussion of technology of this kind must be freefrom bias and it must be based on facts and openness.

We hope that the information that we provide positively affects thecurrent debate. The debate is necessary, but it should be based onfacts and full disclosure of information relevant to the privacyquestion.

>> 6. Do you know how to circumvent Windows Product Activation?

No. We provide insight into which information is transmitted toMicrosoft during activation. Our paper is important to help peopleunderstand the impact of WPA on their work and their privacy. We donot believe that our paper helps in any way to circumvent the licenseenforcement provided by WPA.

>> 7. Your paper says that Microsoft will err on the user's side.

What our paper shows is that a) no sensitive information istransferred to Microsoft and typical hardware upgrades do notnegatively affect an already activated installation of Windows XP.

But, if you either completely re-install Windows XP or modify yourhardware beyond what is tolerated by product activation, you have tore-activate Windows XP.

The important question now is: How often will Microsoft let youre-activate? Erring on the user's side would mean that they allow youto re-activate as often as you like, which seems to be what Microsoftsays they will do.

It is, however, impossible to confirm this policy by means of atechnical analysis.

>> 8. Why doesn't Microsoft know which hardware I use?

Let us consider the case of IDE controllers. In the installation IDtransmitted to Microsoft they are represented by a 4-bit value. The 4bits are obtained by applying the MD5 message digest algorithm to astring that uniquely identifies the vendor and model of the IDEcontroller, e.g.

'PCI\VEN_8086&DEV_7111&SUBSYS_00000000&REV_01'

and picking 4 bits from fixed locations in the resulting 128-bitmessage digest.

With 4 bits, we can represent 16 different values at maximum. However,there are far more than 16 different models of IDE controllers outthere. So, since there are more models than 4-bit values, the abovehashing procedure must yield the same 4 bits for more than onemodel. The more models there are, the more models will map to a given4-bit value.

In contrast to what Microsoft says, the privacy that WPA provides isnot based on the assumption that it is impossible to invert theemployed message digest algorithm, i.e. MD5. If we used all 128 bitsof the message digest derived from a hardware component'sidentification string, this 128-bit value would most probably uniquelyidentify the hardware component. If we used 128 bits, each hardwarecomponent on earth would probably map to a different value.

What an attacker would then do is build a list of all hardwarecomponents on this planet and calculate the corresponding 128-bitvalues, which are probably all different. Then finding the hardwarecomponent that corresponds to a certain 128-bit value is just a tablelookup away.

Privacy is based on the fact that only a few bits of the resulting128-bit message digest are considered. Obviously this leads to lots ofcollisions, i.e. lots of hardware components mapping to a givenvalue. If there were 160 different models of IDE controllers, we couldon average expect 160 / 16 = 10 models to map to the same 4-bit value.

Let us, as another example, consider the MAC address of an ethernetadapter. The discussion is technically not 100% accurate, but itillustrates the point. The MAC address is a 48-bit value, which meansthat it can theoretically be one of 281,474,976,710,656 differentvalues. However, its 10-bit representation in the Installation ID isobtained by picking 10 bits from the MD5 hash over an ASCII stringcomprised of the 12 hex digits of the 48-bit value. Picking 10 bitsleads to 1,024 different results at maximum.

So, on average, we expect

281,474,976,710,656 / 1,024 = 274,877,906,944

MAC addresses to map to the same 10-bit value. Because of this, nobodywill be able to obtain the actual MAC address from the 10-bit value,since there are 274,877,906,944 candidate MAC addresses from which the10-bit value could have been derived.

It is interesting to see that the bit-field that represents the MACaddress is 10 bits in size, while the bit-field representing the IDEcontroller only consists of 4 bits. Microsoft probably have assigned alonger bit-field to a component if they expect more diversity in theidentification string of this component. The number of different IDEcontroller models is smaller by orders of magnitude than the number ofdifferent MAC addresses. So, to produce sufficient collisions, theydecided to use a relatively small bit-field for IDE controllers butcould still afford to chose a 10-bit bit-field in the case of MACaddresses.

>> 9. What are the implications of re-activating after hardwarechanges?

This is an interesting issue which is not covered in our paper. Wesimply did not think of it. Our mistake. It was brought to ourattention by an article by Greg Falcon onwww.slashdot.org: If you have to re-activate your installation ofWindows XP because of hardware modifications, your new hardwareconfiguration is embedded in the Installation ID in the form discussedabove. While this does not enable anyone to find out which componentsyou have, it is trivial to find out which components you havechanged. Just examine which bit-fields have changed their value sincethe original activation.

--------------------------------------------"Windows XP enlists ten hardware components to calculate the installationID, but six of them can be canceled without any problems:

Volume ID ---------- Adapted by means of toolMAC address -------- Tuned by means of driverGraphics card -------Switch over to docking stationCPU serial number - Switch off in BIOSSCSI host adapter -- Switch over to docking stationIDE controller ------- Switch over to docking station

Important: A LAN does not tolerate two computers with the same MAC address."-----------------------------------------(Switching to 'Docking Station' in Device Manager / Performance / FileSystem settings doesn't mean you actually have a docking station of any kindso can be used for non-notebook computers that cannot even USE a dockingstation!)

If you want WindowsXP on a network, you're stuck (until someone findsanother route around Activation - juding by the speed of this one, thatwon't be long!) But then why would anyone want more than one copy of WindozeXP on a LAN anyway!---------------------------------------------"It is more than sufficient to only once activate a computer with 128 MBytesof RAM. With its file wpa.dbl you can then "activate" all other computers ofthe same memory size." [no matter what other hardware is installed as longas it's set as a notebook and the volume tag etc is set to match].

"Can Microsoft be tricked that easily? Yes it can! After the next restart ofthe computer [after changing to docking station] the analysis of theinstallation ID makes clear that suddenly the graphics card and the IDE/SCSIcontroller are no longer used to calculate the hardware ID. In computersthat can be docked, XP ignores the identification of the graphics card, theSCSI host adapter and the IDE controller.

So only three more differences in the configuration of the hardware remain:

Identification of the hard diskIdentification of the CPUIdentification of the CD-ROM drive

Because these three components are allowed to be different without XPinsisting on a new Activation, this should be sufficient. So we copy thefile wpa.dbl into the system32 directory of the second computer and startWindows XP. In the start menu it still says "Activate Windows". But when youcall it up, you get your just reward though:"Windows Product Activation: Windows is already activated. Click OK toexit."

"So first of all Tecchannel saved the file then started changing hardware.Two items OK, but replacing a third - the CPU - triggered the deletion.Although you'd think the CPU is only one component, it's actually tallied upas two. Switching off the CPU serial number in the bios and thereforeknocking it down to one doesn't get the earlier wpa.dbl back - this has beenrestored in a non-activated state.

Copy the saved version back? That surely shouldn't work - but it does. Next,Tecchannel tried a completely new installation using the same product key.This produces a new product ID, but nevertheless copying the wpa.dbl fileback again works.

They also use this file on another computer, altering the computer's volumeID first, which is easily enough done. They can also use forged networkcards MAC addresses, so now they've taken two parts of the hardware ID outof the picture. Next, use the hardware profile to tell the computer it's anotebook with a docking station. This works, and tells WPA to stop countingthe IDE/SCSI controller and the graphics card.

That gets the differences counted down to three, hard disk, CPU and CDROMID, which is within the limit, so WPA is effectively toast.

What does this mean? Tecchannel's investigation shows that, at the veryleast, you can use the same wpa.dbl file to activate as many computers asyou like, provided the RAM size is the same. A 'universal' file that didn'teven require the same RAM might be a possibility, but it's more likely thatpeople will simply swap files to get one appropriate for their hardware. "

Hope it enlights some of us to create a unique keygen just to get the confirmation ID generated after putting the Installation ID on the same.